A photoplethysmogram (PPG) signal can be measured by PPG systems to derive corresponding physiological signals (e.g., pulse rate). In a basic form, PPG systems can employ a light source or light emitter that emits light through an aperture into the user's tissue. In addition, a light detector can be included to receive light through an aperture that reflects off and exits the tissue. However, determination of the user's physiological signals can be erroneous due to variations in the user's skin type, usage conditions, and environmental conditions affecting the signal of the reflected light. Radio Frequency (RF) circuitry can be located in proximity to sensors such as the light detectors of PPG systems, and the RF communication signals from the RF circuitry can interfere with the operation of the sensors by injecting noise into the sensor signals.